Mycological Society of San Francisco. They have meetings on the third Tuesday of the month during the season, and various events are organized. On Monday, Oct 6th, they've organized a "Culinary Group Monthly Dinner" and the weekend of November 14th there's an overnight trip to Mendocino to hunt for mushrooms. If you aren't in San Francisco, there are other mushroom clubs throughout the Bay Area and California. Check the California Mushroom Clubs page here. Or if you're outside of California and would like to get involved with mushroom hunting, go to the North American Mycological Society's Affiliated Clubs page here to find your local mushroom club. There are mushroom clubs in various parts of the USA, and there may be one near you!